CHAPTER 4

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CHAPTER 4

Some Types of Chemical Reactions

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Chapter Four Goals1. The Periodic Table: Metals, Nonmetals, and Metalloids2. Aqueous Solutions: An Introduction3. Reactions in Aqueous Solutions4. Oxidation Numbers

Naming Some Inorganic Compounds5. Naming Binary Compounds6. Naming Ternary Acids and Their Salts

Classifying Chemical Reactions7. Oxidation-Reduction Reactions: An Introduction8. Combination Reactions9. Decomposition Reactions10. Displacement Reactions11. Metathesis Reactions 12. Summary of Reaction Types13. Synthesis Question

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The Periodic Table: Metals, Nonmetals, and Metalloids

1869 - Mendeleev & Meyer Discovered the periodic law

• The properties of the elements are periodic functions of their atomic numbers.

4


Groups or families Vertical group of elements on periodic table Similar chemical and physical properties

5

The Periodic Table: Metals, Nonmetals, and Metalloids Period

Horizontal group of elements on periodic table Transition from metals to nonmetals

6


Some chemical properties of metals1. Outer shells contain few electrons2. Form cations by losing electrons3. Form ionic compounds with nonmetals4. Solid state characterized by metallic

bonding

7


Group IA metals Li, Na, K, Rb, Cs, Fr

One example of a periodic trend The reactions with water of Li

8



One example of a periodic trend The reactions with water of Li, Na

9



One example of a periodic trend The reactions with water of Li, Na, & K

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Group IIA metals alkaline earth metals

Be, Mg, Ca, Sr, Ba, Ra

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Some chemical properties of nonmetals1. Outer shells contain four or more electrons2. Form anions by gaining electrons3. Form ionic compounds with metals and covalent

compounds with other nonmetals4. Form covalently bonded molecules; noble gases

are monatomic

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Group VIIA nonmetals halogens F, Cl, Br, I, At

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Group VIA nonmetals O, S, Se, Te

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Group 0 nonmetals noble, inert or rare gases He, Ne, Ar, Kr, Xe, Rn

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Stair step function on periodic table separates metals from nonmetals.

Metals are to the left of stair step. Approximately 80% of

the elements Best metals are on the

far left of the table.

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Nonmetals are to the right of stair step. Approximately 20% of

the elements Best nonmetals are on

the far right of the table.

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Metalloids have one side of the box on the stair step.

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Periodic trends in metallic character

PeriodicChart

More MetallicMoreMetallic

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Aqueous Solutions: An Introduction

1. Electrolytes and Extent of Ionization Aqueous solutions consist of a solute

dissolved in water. Classification of solutes:

Nonelectrolytes – solutes that do not conduct electricity in water

Examples: C2H5OH - ethanol

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C6H12O6 - glucose (blood sugar)

C

OC

C

C C

C

H

H

OH

H OH

OH

H

OH

OH H

H

H

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C12H22O11 - sucrose (table sugar)

C

OC

C

C C

CH2

H

H

OH

H

OH

OH

HO

H

OH

C C

C

O

C

CH2

H

OH

H

H

OH

CH2

OH

OH

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Aqueous Solutions: An Introduction The reason nonelectrolytes do not

conduct electricity is because they do not form ions in solution.

• ions conduct electricity in solution

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Aqueous Solutions: An Introduction Classification of solutes

strong electrolytes - conduct electricity extremely well in dilute aqueous solutions

Examples of strong electrolytes1. HCl, HNO3, etc.

• strong soluble acids

2. NaOH, KOH, etc.• strong soluble bases

3. NaCl, KBr, etc.• soluble ionic salts• ionize in water essentially 100%

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Aqueous Solutions: An Introduction Classification of solutes

weak electrolytes - conduct electricity poorly in dilute aqueous solutions

1. CH3COOH, (COOH)2 • weak acids

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2. NH3, Fe(OH)3 • weak bases

3. some soluble covalent salts• ionize in water much less than 100%

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2. Strong and Weak Acids Acids are substances that generate

H+ in aqueous solutions. Strong acids ionize 100% in water.

-aqaq

%100g Cl H HCl

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2. Strong and Weak Acids Acids are substances that generate

H+ in aqueous solutions. Strong acids ionize 100% in water.

-

aq3aqOH

3

-aq3aq3

100%2 3

NO + H HNO

or

NO + OH OH HNO

2

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Some Strong Acids and Their Anions Formula Name1. HCl hydrochloric acid2. HBr hydrobromic acid3. HI hydroiodic acid4. HNO3 nitric acid

5. H2SO4 sulfuric acid

6. HClO3 chloric acid

7. HClO4 perchloric acid

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Some Strong Acids and Their Anions Acid Anion Name1. HCl Cl- chloride ion2. HBr Br- bromide ion3. HI I- iodide ion4. HNO3 NO3

- nitrate ion

5. H2SO4 SO42- sulfate ion

6. HClO3 ClO3- chlorate ion

7. HClO4 ClO4- perchlorate ion

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Aqueous Solutions: An Introduction Weak acids ionize significantly less

than 100% in water. Typically ionize 10% or less!

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Some Common Weak Acids and Their Anions Formula Name1. HF hydrofluoric acid2. CH3COOH acetic acid (vinegar)3. HCN hydrocyanic acid4. HNO2 nitrous acid

5. H2CO3 carbonic acid (soda water)

6. H2SO3 sulfurous acid

7. H3PO4 phosphoric acid

8. (COOH)2 oxalic acid

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Some Common Weak Acids and Their Anions Acid Anion Name1. HF F- fluoride ion2. CH3COOH CH3COO- acetate ion3. HCN CN- cyanide ion4. HNO2 NO2

- nitrite ion

5. H2CO3 CO32- carbonate ion

6. H2SO3 SO32- sulfite ion

7. H3PO4 PO43- phosphate ion

8. (COOH)2 (COO)22- oxalate ion

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3. Reversible Reactions CH3COOH acetic acid

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Aqueous Solutions: An Introduction All weak inorganic acids ionize

reversibly or in equilibrium reactions. This is why they ionize less than 100%.

CH3COOH – structure of acetic acid

COH

O

CH3

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Aqueous Solutions: An Introduction Correct chemical symbolism for

equilibrium reactions

aq-aq3

7%

3 H + COOCH COOHCH

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4. Strong Bases, Insoluble Bases, and Weak Bases

Characteristic of common inorganic bases is that they produce OH- ions in solution.

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Common Strong Bases Formula Name1. LiOH lithium hydroxide2. NaOH sodium hydroxide3. KOH potassium hydroxide4. RbOH rubidium hydroxide5. CsOH cesium hydroxide6. Ca(OH)2 calcium hydroxide

7. Sr(OH)2 strontium hydroxide

8. Ba(OH)2 barium hydroxide Notice that they are all hydroxides of IA and IIA metals

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Aqueous Solutions: An Introduction Similarly to strong acids, strong

bases ionize 100% in water.

(aq)OH 2 + (aq)Ba Ba(OH)

(aq)OH + (aq)K KOH-+2

2

-+

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Aqueous Solutions: An Introduction Insoluble or sparingly soluble bases

Ionic compounds that are insoluble in water, consequently, not very basic.

Formula Name1. Cu(OH)2 copper (II) hydroxide

2. Fe(OH)2 iron (II) hydroxide

3. Fe(OH)3 iron (III) hydroxide

4. Zn(OH)2 zinc (II) hydroxide

5. Mg(OH)2 magnesium hydroxide

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Aqueous Solutions: An Introduction Weak bases are covalent compounds that

ionize slightly in water. Ammonia is most common weak base

NH3

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Aqueous Solutions: An Introduction Weak bases are covalent

compounds that ionize slightly in water.

Ammonia is most common weak base NH3

-(aq)aq42g3 OH + NH OH + NH

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5. Solubility Guidelines for Compounds in Aqueous Solutions

It is very important that you know these It is very important that you know these guidelines and how to apply them in reactions.guidelines and how to apply them in reactions.

1) Common inorganic acids and low-molecular-weight organic acids are water soluble.

2) All common compounds of the Group IA metal ions and the ammonium ion are water soluble.

LiLi++, Na Na++, K K++, Rb Rb++, Cs Cs++, and NHNH44++

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Aqueous Solutions: An Introduction3) Common nitrates, acetates, chlorates, and perchlorates are water soluble.

NONO33--, CH CH33COOCOO--, ClO ClO33

--, and ClOClO44--

4) Common chlorides are water soluble. Exceptions – AgClAgCl, Hg Hg22ClCl22, & PbClPbCl22

Common bromides and iodides behave similarly to chlorides. Common fluorides are water soluble.

• Exceptions – MgFMgF22, CaF CaF22, SrF SrF22, BaF BaF22, and PbF PbF22

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Aqueous Solutions: An Introduction5) Common sulfates are water soluble.

Exceptions – PbSO PbSO44, BaSO BaSO44, & HgSO HgSO44

Moderately soluble – CaSO CaSO44, SrSO SrSO44, & Ag Ag22SOSO44

6) Common metal hydroxides are water insolubleinsoluble. Exceptions – LiOH, NaOH, KOH, RbOH LiOH, NaOH, KOH, RbOH & CsOH CsOH

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Aqueous Solutions: An Introduction7) Common carbonates, phosphates, and arsenates are water insolubleinsoluble.

COCO332-2-, PO PO44

3-3-, & AsO AsO443-3-

Exceptions- IA metals IA metals and NH NH44++

Ba(COBa(CO33))22 is moderately soluble is moderately soluble Moderately soluble – MgCO MgCO33

8) Common sulfides are water insolubleinsoluble. Exceptions – IA metals IA metals and NH NH44

++ plus IIA metalsIIA metals

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Reactions in Aqueous Solutions

Symbolic representation of what is happening at the laboratory and molecular levels in aqueous solutions. Copper reacting with silver nitrate.

Laboratory level

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Symbolic representation of what is happening at the laboratory and molecular levels in aqueous solutions. Copper reacting with silver nitrate.

Symbolic representation

s2(aq)3aq3s Ag 2)Cu(NOAgNO 2Cu

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Another example of aqueous reactions. Sodium chloride reacting with silver

nitrate. Laboratory level

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Another example of aqueous reactions. Sodium chloride reacting with silver

nitrate. Symbolic representation

aq3saqaq3 NaNOAgClNaCl AgNO

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There are three ways to write reactions in aqueous solutions.

1. Molecular equation Show all reactants & products in molecular or

ionic form

2. Total ionic equation Show the ions and molecules as they exist in solution

(s)(aq)4(aq)4(s) Cu + ZnSO CuSO + Zn

(s)-2aq4

2aq

-2aq4

2aq(s) Cu +SO+ ZnSO+ Cu+Zn

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3. Net ionic equation Shows ions that participate in reaction

and removes spectator ions. Spectator ions do not participate in

the reaction.

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Reactions in Aqueous Solutions Look in total ionic equation for species

that do not change from reactant to product. Spectator ions in < >’s.

Net ionic equation

(s)-2aq4

2aq

-2aq4

2aq(s) Cu +SO+ ZnSO+ Cu+Zn

(s)2aq

2aq(s) Cu + ZnCu + Zn

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In the total and net ionic equations the only common substances that should be written as ions are:

a. Strong acidsb. Strong basesc. Soluble ionic salts

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Oxidation Numbers Guidelines for assigning oxidation

numbers.1. The oxidation number of any free, uncombined

element is zero.2. The oxidation number of an element in a simple

(monatomic) ion is the charge on the ion.3. In the formula for any compound, the sum of the

oxidation numbers of all elements in the compound is zero.

4. In a polyatomic ion, the sum of the oxidation numbers of the constituent elements is equal to the charge on the ion.

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Oxidation Numbers5. Fluorine has an oxidation number of –1 in its

compounds.6. Hydrogen, H, has an oxidation number of +1

unless it is combined with metals, where it has the oxidation number -1.

Examples – LiH, BaH2

7. Oxygen usually has the oxidation number -2. Exceptions: In peroxides O has oxidation number of –1.

• Examples - H2O2, CaO2, Na2O2

In OF2 O has oxidation number of +2.

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Oxidation Numbers8. Use the periodic table to help with

assigning oxidation numbers of other elements.

a. IA metals have oxidation numbers of +1.b. IIA metals have oxidation numbers of +2.c. IIIA metals have oxidation numbers of +3.

• There are a few rare exceptions.d. VA elements have oxidation numbers of –3 in binary

compounds with H, metals or NH4+.

e. VIA elements below O have oxidation numbers of –2 in binary compounds with H, metals or NH4

+. Summary in Table 4-10.

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Oxidation Numbers Example 4-1: Assign oxidation numbers to

each element in the following compounds: NaNO3 Na = +1 (Rule 8) O = -2 (Rule 7) N = +5

Calculate using rule 3. +1 + 3(-2) + x = 0 x = +5

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Oxidation Numbers K2Sn(OH)6

K = +1 (Rule 8) O = -2 (Rule 7) H = +1 (Rule 6) Sn = +5

Calculate using rule 3. 2(+1) + 6(-2) + 6(+1) + x = 0 x = +5

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Oxidation Numbers

HClO4

You do it!You do it! H = +1 O = -2 Cl = +7

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Oxidation Numbers

NO2-

O = -2 (Rule 7) N = +3

Calculate using rule 4. 2(-2) + x = -1 x = +3

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Oxidation Numbers

HCO3-

O = -2 (Rule 7) H = +1 (Rule 6) C = +4

Calculate using rule 4. +1 + 3(-2) + x = -1 x = +4

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Oxidation Numbers

(COOH)2

You do it!You do it! H = +1 O = -2 C = +3

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Naming Some Inorganic Compounds Binary compounds are made of two

elements. metal + nonmetal = ionic compound nonmetal + nonmetal = covalent compound

Name the more metallic element first. Use the element’s name.

Name the less metallic element second. Add the suffix “ide” to the element’s stem.

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Naming Some Inorganic Compounds Nonmetal StemsNonmetal Stems Element Stem Boron bor Carbon carb Silicon silic Nitrogen nitr Phosphorus phosph Arsenic arsen Antimony antimon

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Naming Some Inorganic Compounds Oxygen ox Sulfur sulf Selenium selen Tellurium tellur Phosphorus phosph Hydrogen hydr

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Naming Some Inorganic Compounds Fluorine fluor Chlorine chlor Bromine brom Iodine iod

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Naming Some Inorganic Compounds

Binary Ionic Compounds Binary Ionic Compounds are made of a metal cation and a nonmetal anion. Cation named first Anion named second

LiBr lithium bromide MgCl2 magnesium chloride

Li2S lithium sulfide

Al2O3 You do it!You do it!

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Naming Some Inorganic Compounds LiBr lithium bromide MgCl2 magnesium chloride Li2S lithium sulfide Al2O3 aluminum oxide

Na3P You do it!You do it!

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Naming Some Inorganic Compounds LiBr lithium bromide MgCl2 magnesium chloride


Al2O3 aluminum oxide

Na3P sodium phosphide

Mg3N2 You do it!You do it!

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Naming Some Inorganic Compounds LiBr lithium bromide MgCl2 magnesium chloride


Al2O3 aluminum oxide

Na3P sodium phosphide

Mg3N2 magnesium nitride Notice that binary ionic compounds with metals

having one oxidation state (representative metals) do not use prefixes or Roman numerals.

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Naming Some Inorganic Compounds Binary ionic compounds Binary ionic compounds

containing metals that exhibit containing metals that exhibit more than one oxidation statemore than one oxidation state

Metals exhibiting multiple oxidation states are:1. most of the transition metals2. metals in groups IIIA (except Al), IVA,

& VA

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Naming Some Inorganic Compounds There are two methods to name these

compounds.1. Older method

add suffix “ic” to element’s Latin name for higher oxidation state

add suffix “ous” to element’s Latin name for lower oxidation state

2. Modern method use Roman numerals in parentheses to

indicate metal’s oxidation state

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Compound Old System Modern System FeBr2 ferrous bromide iron(II) bromide

FeBr3 ferric bromide iron(III) bromide SnO stannous oxide tin(II) oxide SnO2 stannic oxide tin(IV) oxide

TiCl2 You do it!You do it!

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TiCl2 titanous chloride titanium(II) chloride


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TiCl3 titanic chloride titanium(III) chloride


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TiCl3 titanic chloride titanium(III) chloride

TiCl4 does not workdoes not work titanium(IV) chloride

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Pseudobinary ionic compoundsPseudobinary ionic compounds There are three polyatomic ions that commonly form

binary ionic compounds.1. OH- hydroxide2. CN- cyanide3. NH4

+ ammonium Use binary ionic compound naming system. KOH potassium hydroxide Ba(OH)2 barium hydroxide Al(OH)3 aluminum hydroxide Fe(OH)2 You do it!You do it!

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Naming Some Inorganic Compounds KOH potassium hydroxide Ba(OH)2 barium hydroxide

Al(OH)3 aluminum hydroxide

Fe(OH)2 iron (II) hydroxide

Fe(OH)3 You do it!You do it!

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Fe(OH)3 iron (III) hydroxide

Ba(CN)2 You do it!You do it!

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Fe(OH)3 iron (III) hydroxide

Ba(CN)2 barium cyanide

(NH4)2S You do it!You do it!

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Naming Some Inorganic Compounds KOH potassium hydroxide Ba(OH)2 barium hydroxide Al(OH)3 aluminum hydroxide Fe(OH)2 iron (II) hydroxide Fe(OH)3 iron (III) hydroxide Ba(CN)2 barium cyanide (NH4)2S ammonium sulfide NH4CN You do it!You do it!

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Naming Some Inorganic Compounds KOH potassium hydroxide Ba(OH)2 barium hydroxide Al(OH)3 aluminum hydroxide Fe(OH)2 iron (II) hydroxide Fe(OH)3 iron (III) hydroxide Ba(CN)2 barium cyanide (NH4)2S ammonium sulfide NH4CN ammonium cyanide

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Naming Some Inorganic Compounds Binary Acids Binary Acids are binary compounds

consisting of hydrogen and a nonmetal. Compounds are usually gases at room

temperature and pressure. Nomenclature for the gaseous compounds is

hydrogen (stem)ide. When the compounds are dissolved in

water they form acidic solutions. Nomenclature for the acidic solutions is hydro (stem)ic acid.

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Formula Name Aqueous Solution

HF hydrogen fluoride hydrofluoric acid HCl hydrogen chloride hydrochloric acid HBr hydrogen bromide hydrobromic acid H2S You do it!You do it!

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Formula Name Aqueous solution HF hydrogen fluoride hydrofluoric acid HCl hydrogen chloride hydrochloric acid HBr hydrogen bromide hydrobromic acid H2S hydrogen sulfide hydrosulfuric acid

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Binary covalent molecular Binary covalent molecular compounds composed of two compounds composed of two nonmetals other than hydrogennonmetals other than hydrogen Nomenclature must include prefixes that

specify the number of atoms of each element in the compound.

Use the minimum number of prefixes necessary to specify the compound. Frequently drop the prefix mono-.

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Naming Some Inorganic Compounds Formula Name CO carbon monoxide CO2 carbon dioxide

SO3 sulfur trioxide

OF2 oxygen difluoride

P4O6 You do it!You do it!

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SO3 sulfur trioxide


P4O6 tetraphosphorus hexoxide

P4O10 You do it!You do it!

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SO3 sulfur trioxide


P4O6 tetraphosphorus hexoxide

P4O10 tetraphosphorus decoxide

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The oxides of nitrogen illustrate why covalent compounds need prefixes and ionic compounds do not.

Formula Old Name Modern Name N2O nitrous oxide dinitrogen monoxide NO nitric oxide nitrogen monoxide N2O3 nitrogen trioxide dinitrogen trioxide

NO2 nitrogen dioxide nitrogen dioxide

N2O4 nitrogen tetroxide dinitrogen tetroxide

N2O5 nitrogen pentoxide dinitrogen pentoxide

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Ternary Acids and Their Salts Ternary Acids and Their Salts are made of three elements. The elements are H, O, & a nonmetal.

Two of the compounds are chosen as the basis for the nomenclature system. Higher oxidation state for nonmetal is named (stem)ic

acid. Lower oxidation state for nonmetal is named

(stem)ous acid Salts are named based on the acids.

Anions of -ic acids make “ate” salts. Anions of -ous acids make “ite” salts.

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Names and Formulas of the Common “ic” acids Naming these compounds will be easier if you have this

list memorized. Group Name Formula IIIA boric acid H3BO3

IVA carbonic acid H2CO3

silicic acid H4SiO4

VA nitric acid HNO3

phosphoric acid H3PO4

arsenic acid H3AsO4

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VIA sulfuric acid H2SO4

selenic acid H2SeO4

telluric acid H6TeO6

VIIA chloric acid HClO3

bromic acid HBrO3

iodic acid HIO3

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Naming Some Inorganic Compounds Salts are formed by the reaction of the

acid with a strong base. Acid Salt HNO2 NaNO2

nitrous acid sodium nitrite HNO3 NaNO3

nitric acid sodium nitrate H2SO3 Na2SO3

sulfurous acid sodium sulfite

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Naming Some Inorganic Compounds Acid Na Salt H2SO4 You do it!You do it!

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Naming Some Inorganic Compounds Acid Na salt H2SO4 Na2SO4

sulfuric acid sodium sulfate

HClO2 You do it!You do it!

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HClO2 NaClO2

chlorous acid sodium chlorite

HClO3 You do it!You do it!

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HClO2 NaClO2

chlorous acid sodium chlorite

HClO3 NaClO3

chloric acid sodium chlorate

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Naming Some Inorganic Compounds There are two other possible acid and salt

combinations. Acids that have a higher oxidation state than

the “ic” acid are given the prefix “per”. These acids and salts will have one more O atom

than the “ic” acid. Acids that have a lower oxidation state than

the “ous” acid are given the prefix “hypo”. These acids and salts will have one less O atom

than the “ous” acid.

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Naming Some Inorganic Compounds Illustrate this series of acids and salts with the Cl

ternary acids and salts. Acid Na Salt HClO NaClO

hypochlorous acid sodium hypochlorite HClO2 NaClO2

chlorous acid sodium chlorite HClO3 NaClO3

chloric acid sodium chlorate HClO4 NaClO4

perchloric acid sodium perchlorate

101


Acidic SaltsAcidic Salts are made from ternary acids that retain one or more of their acidic hydrogen atoms. Made from acid base reactions where there is

an insufficient amount of base to react with all of the hydrogen atoms.

Old system used the prefix “bi”“bi” to denote the hydrogen atom.

Modern system uses prefixes and the word hydrogen.

102


NaHCO3 Old system sodium bicarbonate Modern system sodium hydrogen carbonate

KHSO4 Old system potassium bisulfate Modern system potassium hydrogen sulfate

KH2PO4

Old system potassium bis biphosphate Modern system potassium dihydrogen phosphate

K2HPO4 You do it!You do it!

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K2HPO4 Old system potassium biphosphateModern system potassium hydrogen phosphate

104

Naming SomeInorganic Compounds Basic SaltsBasic Salts are analogous to acidic salts.

The salts have one or more basic hydroxides remaining in the compound.

Basic salts are formed by acid-base reactions with insufficient amounts of the acid to react with all of the hydroxide ions.

Use prefixes to indicate the number of hydroxide groups.

105

Naming SomeInorganic Compounds Ca(OH)Cl

calcium monohydroxy chloride

Al(OH)Cl2 aluminum monohydroxy chloride

Al(OH)2Cl You do it!You do it! aluminum dihydroxy chloride

106

Oxidation-Reduction Reactions: An Introduction Oxidation is an increase in the

oxidation number. Corresponds to the loss of electrons.

Reduction is a decrease in the oxidation number. Good mnemonic – reduction reduces

the oxidation number. Corresponds to the gain of electrons

107

Oxidation-Reduction Reactions: An Introduction

Oxidizing agents are chemical species that:1. oxidize some other substance2. contain atoms that are reduced in the reaction 3. gain electrons

Reducing agents are chemical species that:1. reduce some other substance 2. contain atoms that are oxidized in the reaction3. lose electrons

108


Two examples of oxidation-reduction or redox reactions.

KMnO4 and Fe2+

Fe2+ is oxidized to Fe3+

MnO41- is reduced to Mn2+

Combustion reactions are redox reactions Combustion of Mg

Mg is oxidized to MgO O2 is reduced to O2-

109


Example 4-2: Write and balance the formula unit, total ionic, and net ionic equations for the oxidation of sulfurous acid to sulfuric acid by oxygen in acidic aqueous solution.

Formula unit equation

Total ionic equationYou do it!You do it!

aq42g2aq32 SO H2 O SO H2

2

4(aq)(aq)g2aq32 SO 2 H 4 O SOH 2

110

Oxidation-Reduction Reactions: An Introduction Net ionic equation

You do it!You do it!

Which species are oxidized and reduced? Identify the oxidizing and reducing agents.


2

4(aq)(aq)g2aq32 SO 2 H 4 O SOH 2

111

Oxidation-Reduction Reactions: An Introduction H2SO3 is oxidized.

The oxidation state of S in H2SO3 is +4.

In SO42-, S has an oxidation state of +6.

O2 is reduced. Oxidation state of O in O2 is 0

In SO42-, O has an oxidation state of –2.

H2SO3 is reducing agent.

O2 is oxidizing agent.

112

Combination Reactions Combination reactions occur when two

or more substances combine to form a compound.

There are three basic types of combination reactions.

1. Two elements react to form a new compound

2. An element and a compound react to form one new compound

3. Two compounds react to form one compound

113

Combination Reactions

1. Element + Element CompoundA. Metal + Nonmetal Binary Ionic Compound

sg2s NaCl 2ClNa 2

114



sg2s MgO 2OMg 2

115



s32s AlBr 2 Br3Al 2

116


1. Element + Element CompoundB. Nonmetal + Nonmetal Covalent Binary

Compound

s104g2s4 O PO 5P

117



Compound

3g2s4 PCl4 Cl 6P

118



Compound• Can control which product is made with the

reaction conditions.

chlorine limitedin

AsCl 2 Cl 3As 2 s3g2s

chlorine excessin

AsCl 2 Cl 5As 2 s5g2s

119



Compound• Can control which product is made with

the reaction conditions.

fluorine limitedin

SeF F 2Se s4g2s

fluorine excessin

SeF F 3Se g6g2s

120


2. Compound + Element Compound

s5g2s3 AsClClAsCl

g6g2s4 SFFSF

121


The reaction of oxygen with oxides of nonmetals is an example of this type of combination reaction.

g3 &catalyst

g2g2 SO 2OSO 2

g2g2g CO 2OCO 2

104264 OPO 2OP

122


3. Compound + Compound Compound gaseous ammonia and hydrogen chloride

lithium oxide and sulfur dioxide

s4gg3 ClNH HClNH

3222 SO LiSOOLi

123

Decomposition Reactions Decomposition reactions occur

when one compound decomposes to form:

1. Two elements2. One or more elements and one or

more compounds3. Two or more compounds

124

Decomposition Reactions

1. Compound Element + Element decomposition of dinitrogen oxide

decomposition of calcium chloride

g2g2g2 ON 2ON 2

g2yelectricit

2 ClCaCaCl

2sh

s BAg 2AgBr 2 r

decomposition of silver halides

125


2. Compound One Element + Compound(s)

decomposition of hydrogen peroxide

g22or Mn or Feνh

aq22 OO H2O H23

126


3. Compound Compound + Compound decomposition of ammonium hydrogen

carbonate

g2g2g3s34 COO HNHHCONH

127

Displacement Reactions Displacement reactionsDisplacement reactions occur

when one element displaces another element from a compound. These are redox reactions in which the

more active metal displaces the less active metal of hydrogen from a compound in aqueous solution.

Activity series is given in Table 4-14.

128

Displacement Reactions1. [More Active Metal + Salt of Less Active Metal]

[Less Active Metal + Salt of More Active Metal] molecular equation

(s)aq3(s) aq3 Ag CuNO Cu +AgNO

129

Displacement Reactions Total ionic equation


Net ionic equationYou do it!You do it!

(s)-

aq3aqs-

aq3aq Ag NO+CuCu +NO+ Ag

(s)aq(s)aq Ag Cu Cu +Ag

130

Displacement Reactions2. [Active Metal + Nonoxidizing Acid] [Hydrogen +

Salt of Acid] Common method for preparing hydrogen in the laboratory. HNO3 is an oxidizing acid.

Molecular equation

g2aq342aq42(s) H 3 + )(SOAl SO3H + Al 2

131

Displacement Reactions Total ionic equation


Net ionic equationYou do it!You do it!

g2-2aq4

3aq

-2aq4aq(s) H 3 + SO 3 + Al 2 SO 3+H 6 + Al 2

g23aqaq(s) H 3 +Al 2 H 6 + Al 2

132

Displacement Reactions The following metals are active

enough to displace hydrogen K, Ca, Na, Mg, Al, Zn, Fe, Sn, & Pb

Notice how the reaction changes with an oxidizing acid. Reaction of Cu with HNO3.

• H2 is no longer produced.

133

Displacement Reactions3. [Active Nonmetal + Salt of Less Active Nonmetal]

[Less Active Nonmetal + Salt of More Active Nonmetal]

Molecular equation

(aq)s2aqg2 NaCl 2 I NaI 2 + Cl Total ionic equation


-aqaqs2

-aqaqg2 Cl 2 +Na 2 I I 2 + Na 2 +Cl

134

Displacement Reactions Net ionic equation


-aqs2

-aqg2 Cl 2 I I 2 +Cl

135

Metathesis Reactions Metathesis reactionsMetathesis reactions occur when two

ionic aqueous solutions are mixed and the ions switch partners.

AX + BY AY + BX Metathesis reactions remove ions from

solution in two ways:1. form predominantly unionized molecules like

H2O2. form an insoluble solid

Ion removal is the driving force of metathesis reactions.

136

Metathesis Reactions

1. Acid-Base (neutralization) Reactions Formation of the nonelectrolyte H2O acid + base salt + water

137

Metathesis Reactions Molecular equation

)(2 (aq)(aq)(aq) OH + KBr KOH + HBr Total ionic equation


)(2-aqaq

-aqaq

-aqaq OH + Br+KOH+K+Br+H

Net ionic equation


)(2-aqaq OH OH +H

138


)(2aq)(23(aq)3(aq)2 OH 2 + )Ca(NOHNO 2 + Ca(OH) Total ionic equation

You do it!You do it! )(2

-aq3

2aq

-aq3aq

-aq

2aq OH 2 +NO 2+ CaNO 2+ H 2+OH 2+Ca

Net ionic equation


)(2aq-aq

)(2aq-aq

OH H+OH

betteror

OH 2 H 2+OH 2

139

Metathesis Reactions

2.2. Precipitation reactionsPrecipitation reactions are metathesis reactions in which an insoluble compound is formed.

The solid precipitates out of the solution much like rain or snow precipitates out of the air.

140

Metathesis Reactions Precipitation Reactions Molecular equation

(s)3)aq(3aq)(32(aq)23 CaCO +KNO 2 COK + )Ca(NO Total ionic reaction


s3-

aq3aq

-2aq3aq

-aq3

2aq

CaCO NO 2K 2

COK 2 NO 2 Ca

141

Metathesis Reactions Net ionic reaction


(s)3-2aq3

2aq CaCO CO +Ca

142


2(s)43)aq(aq)(43(aq)2 POCa +NaCl 6 PONa 2 + CaCl 3

Total ionic reactionYou do it!You do it!

s243-1aq

1aq

-3aq4

1aq

-1aq

2aq

POCa +Cl 6 Na 6

PO2 Na 6 + Cl 6 Ca 3

143



s243-3aq4

2aq POCa PO 2 Ca 3

144


g22)aq(aq)(32(aq) SO O H+NaCl 2 SONa + HCl2

Total ionic reactionYou do it!You do it!

g22-1aq

1aq

-2aq3

1aq

-1aq

1aq

SO OH +Cl 2Na 2

SO Na 2 + Cl 2H 2

145



146

End of Chapter 4

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CHAPTER 4

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